Manhole-cover plate



FIPBZLZ Feh 4, 1930.

J. F. GRACE muons covsn PLAT! Filed Oct. 24. 1927 NTOR JOHN F. GRACE. I

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Patented Feb. 4, 1930 PATENT OFFICE JOHN F. GRACE, OF ARLINGTON, NEW JERSEY, ASSIGNOR TO WORTI-IINGTON PUMP AND MACHINERY CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF VIRGINIA MAN HOLE-COVER PLATE Application filed October 24, 1927. Serial No. 228,192.

This invention relates to cover or closure plates for manholes in stills or analogous apparatus in which the maintenance of a vacuum is important, and an object of the in- 5 vention is to provide a manhole cover plate operating under the high vacuum principle,

the importance of minimizing air leakage de mands close attention, as in high vacuum equipment, subjected to high temperatures necessary in oil distillation, any air leaking into the oil heated above the fire point produces small local flames within the stills and oxidizes and cracks portions of the oil exposed to the air currents, and in the production of lubricants it is particularly important that cracking shall be minimized.

The present invention comprises a man hole cover plate structure embodying an inner plate fitted in any suitable manner to the still or container and a tightly bolted outer plate spaced from the inner plate to provide an intermediate chamber which is filled with liquid to provide a seal, and such liquid may be under pressure greater than atmosphere to effectively seal the joints against air leakage. I

With these objects in View, the invention consists in various features of construction and combination of parts, which will be first described in connection with the accompanying drawings, showing a manhole cover plate minimize air leakage into the container 1 through the manhole.

The cover plate structure includes an endless ring gasket 3 which is welded or otherwise suitably attached to the container 1 and which is provided with an annular groove 4: into which the in-turned edge 5 of the inner plate 6 engages. The inner plate 6 is tightly bolted in place by means of bolts 7 and it may be hinged by any suitable type of hinge as shown at 8.

An outer plate 9 is provided which is tightly bolted by means of bolts 10 extending from the bosses 11 to the gasket 3 and the outer plate 9 is spaced from the inner plate 6 so as to provide an intermediate chamber 12 which contains a liquid to provide a liquid seal for the joints in the manhole cover. In F 1 of the drawings the outer plate 9 is shown as provided with hollow extensions 14: and 15 which open out into the chamber 12. Inlet and outlet pipes 16 and 17 respectively connect with the hollow extensions 14 and 15 to permit the entrance and exit of fluid under pressure into or from the chamber 12. The sealing liquid in the chamber 12 may be circulated or it may be forced therein and remain relatively stationary. It is preferable that the sealing liquid in the chamber 12 be under pressure greater than atmospheric pressure or greater than the pressure surrounding the outside of the still or container 1.

The cover plate 9 may be hinged by any suitable type of hinge as indicated at 18, also if it is so desired, pipes 16 and 17 may have swivel connections or may be of such material as to permit the free opening of the cover plate 9 without affecting the connections between the extensions 14 and 15 and the respective pipes 16 and 17. If it is so desired. the cover plate 9 may be provided with a drain block 19 and a vent block 20 to permit the draining of the fluid therefrom.

The gasket 3 and the inner plate 6 are preferably of metals having different co-efficients of expansion, such as aluminium for the gasket and steel for the inner plate 6, so that the spring of the steel inner plate will comer s pensate for expansion under high temperatures.

While in the foregoing description the improved manhole cover has been described as particularly applicable for use in apparatus employed in the distilling of petroleum oils or the like, it is to be understood that the improved cover is applicable for use with various other structures, where it is desired to prevent leakage of air into the structure with which the cover is associated without departing from the spirit of this invention.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that these may be modified widely within the invention defined by the claims.

lVhat is claimed is:

1. A manhole cover, comprising an inner plate, an outer plate enclosing the inner plate and spaced therefrom to provide a chamber, and a sealing liquid in said chamber and forming a sealing about the outer edge of the inner plate and the inner edge of the outer plate.

2. The combination with a container having an opening therein, of a cover for said opening comprising an inner plate forming a closure for the opening, an outer plate enclosing said inner plate and spaced therefrom to provide a chamber, said chamber having an inlet and an outlet to permit circulation of fluid under pressure in the chamber.

3. The combination with a container having an opening therein, of a gasket about the opening, a cover for said openin comprising an inner plate forming a closure for the opening, an outer plate enclosing said in ner plate and spaced therefrom to provide a chamber, and a sealing liquid in said chamber to provide a seal for the joints of connection between said plates and said gasket.

4. The combination with a container having an opening therein, of a gasket about the opening, a cover for said opening comprising an inner plate forming a closure for the opening, an outer plate enclosing said inner plate and spaced therefrom to provide a chamber, and a sealing liquid in said chamber to provide a seal for the joints of connection between said plates and said gasket, said sealing liquid being under pressure greater than atmosphere.

5. The combination with a container adapted to contain fluid under high pressure and having an opening therein, of a gasket about the opening. a cover for said opening engaging said gasket, an outer plate enclosing said inner plate and spaced therefrom to provide a chamber, a sealing liquid in said chamber to provide a sealing for the joints of connection between said plates and gasket, said gasket and inner plate made of metals of clifferent coefficients of expansion to compensate for expansion and contraction of the parts under heat variances.

6. The combination with a container hav ing an opening therein, a closure plate forming a closure for the opening, a second plate enclosing the inner plate and spaced therefrom to provide a chamber, said chamber having a sealing liquid underpressure therein to provide a sealing for the joints of connection of said plates with the container.

7. A manhole cover adapted for service which will subject it to a wide range of temperatures comprising an inner plate, an outer plate enclosing the inner plate and spaced therefrom to provide a chamber, a gasket engaged by the edge of said outer plate said gasket and inner plate made of metals of different coeflicients of expansion to compensate for expansion and contraction under heat variances, and a sealing liquid under pressure greater than the pressure exteriorly of said outer plate in said chamber and forming pressure seals for the inner edge of the outer plate and the connection of the inner plate and gasket.

In testimony whereof I afiix my signature.

JOHN F. GRACE. 

